A former San Francisco police detective suffering from an extreme case of obsessive-compulsive disorder is called in to investigate an apparent assassination attempt of a mayoral candidate in which one of his bodyguards is killed.
With an introduction to Monk's talent, his phobias, and his need for an assistant, Monk investigates the murder of the candidate bodyguard and a political worker. He determines the candidate was not the intended target.
When a woman drives off the road to her death, her body is mysteriously found the next morning by a psychic known for fudging the truth. Monk must discover if she's telling the truth this time, or else let a murderer go free.
A judge is murdered while placing a 911 call, but before she dies she names her attacker - notorious criminal Dale Biederbeck. The problem is, "Dale the Whale" is over 800 pounds and hasn't left his bed in years.
When billionaire software magnate Sidney Teal is shot dead by ex-cop Archie Modine after allegedly turning mugger and another policeman mysteriously flees the scene, Stottlemeyer calls in Monk to investigate. Not only is the idea of a billionaire turning mugger hard to swallow, the circumstances of the mugging are suspicious. Why, for example, would a mugger wear knee and elbow pads? Meanwhile, Sharona threatens to quit (this time for sure) when her paycheck bounces, and Stottlemeyer is hounded by reporters demanding information on "Fraidy Cop." Unable to continue the investigation without Sharona's help, Monk returns to the seemingly unsolvable mystery of his wife's murder only to find that his "new" clue isn't new; he's already talked to writer Kelly Street three times. Sharona finds that selling lamps isn't nearly as much fun as working for Monk (with or without money) and comes to the rescue with a new clue involving Teal and Modine.
While on vacation at a resort, Benjy claims he witnessed a murder. Monk believes him, but with no body and the cleanest crime scene Monk has ever seen, it's going to be hard to convince everybody else.
Renowned philanthropist Henry Rutherford is killed when a moderate earthquake rocks the city and sends a display case falling on top of him. But when Monk examines the scene, he finds clues that suggest foul play.
When English teacher Beth Landow falls from the clock tower at Trudy's former high school, Monk is called in and quickly disproves the police theory of suicide. The trail of clues leads to a science teacher but he has an iron-clad alibi. Monk becomes a substitute teacher in the hopes of solving the case.
A skydiving student on spring break appears to have drowned in midair - a case strange enough to convince Monk to travel to Mexico to investigate. While there, he must deal with a myriad of phobias, the theft of his luggage, the shortage of his favorite brand of bottled water, and apparent attempts on his life, all while trying to unravel one or more murders that are not what they seem.
When a powerful CEO and his wife are shot to death in a deserted parking lot, the police investigate the husband's enemies. But Monk thinks it's all about the wife and the affair she was having with a handsome young ballplayer.
The world's oldest man dies the day before his birthday, and everyone but Stottlemeyer's wife, Karen, thinks it's just the result of old age. Karen enlists Monk's help to figure out what really happened.
When Randy's mother marries a guy much younger than her he gets worried. When they go to some kind of couples retreat, he asks Monk and Sharona to go and keep an eye on her. So to go in they pretend to be married.
Karen Stottlemeyer films a documentary of Captain Stottlemeyer's division. Despite the Commissioner's objections, Monk helps solve the case of a headless corpse, a fatal fire at a wig factory, and a hat thief all in one fell swoop.
A mob boss needs Monk's help to figure out who murdered some members of the family. Monk reluctantly takes the case when the FBI offers to help get him reinstated in exchange for the information he gathers.
Sharona takes a break from Monk so that she can concentrate on her creative writing class, but gets caught up in a twisted murder plot that causes her to question her sanity. Meanwhile, Monk is distracted by Sharona's replacement, who is determined to fix him.
Monk goes undercover at a department store to investigate the mysterious death of a popular store employee. In the process he also gains valuable insights into the life of his former partner, who happens to be the store's head of security.
Trudy's father, a game show producer, invites Monk to Hollywood to determine if the host is helping a contestant cheat. Monk has to become a contestant himself in order to clinch the case, as well as to confirm his suspicions about the death of the host's assistant.
A woman commits suicide and minutes later Captain Stottlemeyer is shot nearby. Monk needs to determine if the two events are related, but his new medication has turned him into an obnoxious jerk who can't concentrate on the case.
Monk is having a hard time finding a new assistant, and Natalie might be just what he is looking for. But first he has to take her case and solve the mystery of the intruder who seems inordinately interested in her daughter's pet fish.
When an author of a book debunking the career of a popular martial-arts movie star is killed, the evidence points to the star himself, despite the fact that he has been dead for years! Monk takes the case and also gets a chance to prove to Natalie that he is not as selfish as he seems.
As sole witness to a murder, Monk is shuffled off to a safe location until he can give a deposition. When a man is killed by lightning while fishing on the lake outside his cabin, however, Monk believes there's more to the man's death than meets the eye.
A motley assortment of commuters, including Monk and the gang, are stuck on the highway after a fatal car accident brings traffic to a dead halt. But Monk doesn't think it was any accident and his impromptu investigation irritates authorities at the scene.
On Halloween, Monk visits his brother Ambrose in his childhood home to await a visit from his long-absent father, but things take a strange turn when a masked trick-or-treater repeatedly tries to steal Halloween candy from Ambrose's house.
When Natalie finally catches up with the pizza guy who mistakenly left her $50 in change, she finds him dead in his car. She feels compelled to solve the murder but Monk, sick in bed, offers little help.
Monk goes undercover as an office worker and revels in the office routines and actually starts making friends and a possible romance as he tries to solve a murder that occurred in a parking garage next to the office building as well as who injured the hand of the man who hired him whose hand was slammed into a car door probably by the murderer. But Monk's new found popularity may come to a screeching halt if he won't put on the pair of used bowling shoes for the showdown match between his office team and their rival team.
While investigating a murder, Stottlemeyer gets into an argument with a cop at the scene who snidely tells him he has been seeing his wife. As a result the crime scene was deemed contaminated. He later asks Monk to follow his wife to see if it's true.
Lt. Disher and Captain Stottlemeyer capture a "Most Wanted", Columbian criminal, Miguel Escobar, who's wanted for drug trafficking crimes in multiple states, and arrest him for a local homicide. Escobar is notorious for escaping custody, so Stottlemeyer must take extra precautions to ensure that this does not happen while Escobar is in his custody. Captain Stottlemeyer learns that the US Attorney General is ordering him to turn over Escobar to the Federal Government, and is to do nothing more than detain their prisoner until the hand-off, following an extradition hearing. This takes place in the same courthouse where, much to his dismay, Mr. Monk is unable to talk his way out of jury duty, and finds himself forced to hear the case of a robbery/stabbing of a man out to make a bank deposit. During the course of deliberating the robbery case, however, Monk is inadvertently pulled into the Escobar saga.
Upset when a hiring freeze at the police department is announced, Monk is pressured by Natalie to investigate the deaths of her parents' neighbors, but when Monk starts considering his undercover role as a viable alternate career something has to be done.
Monk goes to the emergency room with a persistent nose bleed, which he becomes convinced is actually a cerebral hemorrhage, and discovers the doctor he sought out for second opinion, dead on his office floor.
A boxer narrowly avoids a bomb, and Stottlemeyer believes it won't be the only attempt with a championship bout coming up. Meantime, Monk splits his time between the case and contemplating retirement when he finds he must pass a fitness exam.
Monk is smitten with an attractive former dancer and when she's accused of murder, he agrees to help her, even though all the evidence points to her, and continues searching--even after she confesses to the crime.
When Monk's half-brother Jack shows up at his door, he's less than thrilled, especially after learning that Jack has just escaped from prison and is accused of killing a very popular female employee while making his escape.
Monk gets a call from a man who bullied him when he was a kid. He's still affected by it. He's uneasy when he goes to see him. The man wants to hire Monk to follow his wife who he suspects is hiding something from him. Monk accepts to rub his nose in it. And when he follows her he discovers she's hiding something but Monk thinks there's more going on.
Desperate to save the parking lot where Trudy was killed from demolition, Monk enlists the help of a sympathetic councilwoman. But when she goes missing, Monk may be forced to deal with her hapless and incapable assistant.
After Stottlemeyer, Disher and Monk are shredded on the stand in a murder case, causing the accused to go free, Monk loses his confidence. Meanwhile, Disher tries to help a boy he used to mentor who is accused of another murder.
Sharona's big payday is in jeopardy when Monk believes her uncle was murdered, rather than killed by an accidental fall, and the investigation will test everyone's tempers as Natalie and Sharona mark their territories.
In an attempt to woo the lone holdout on the reinstatement committee, Monk accompanies the man's troublesome son and Randy's camping group - where they soon find themselves running afoul of some dangerous armored car robbers.